Tips?

Hello everyone! I’ve just joined. I started writing my first book when I was 12, and have always had my family’s support. I’ve been told my writing is good, however, I always know there’s room for improvement. My first book was written pen to paper in a series of notebooks that have since been lost to time, and I’d like to start again after so long. I’m just looking for tips, words of encouragement, or little pieces of advice for a beginner! I’m super nervous about starting again, and I’m afraid I won’t be interesting enough or something. I have major plot points already decided, it’s just……the in between stuff I’m seeming to have issues with. I still want it to be interesting so that readers don’t get bored halfway through, so…….I guess, what’s some advice you guys may have? What’s your experience been like while writing?